Radar Kilometer / Radar Nautical Mile

Radar timing is usually expressed in microseconds. To relate radar timing to distances
traveled by radar energy, you should know that radiated energy from a radar set travels
at approximately 984 feet per microsecond. With the knowledge that a nautical mile is
approximately 6,080 feet, we can figure the approximate time required for radar energy
to travel one nautical mile using the following calculation:

A pulse-type radar set transmits a short burst of electromagnetic energy. Target range
is determined by measuring elapsed time while the pulse travels to and returns from the
target. Because two-way travel is involved, a total time of 12.36 microseconds
per nautical mile will elapse between the start of the pulse from the antenna and its
return to the antenna from a target.

This 12.36 microsecond time interval is sometimes referred to as a RADAR MILE,
RADAR NAUTICAL MILE, or NAUTICAL RADAR MILE.

1 Radar Kilometer =

2 · 1000 m

= 6.66 µs

(1)

3 · 108 m/s

1 Radar Mile =

2 · 1852 m

= 12.35 µs

(2)

3 · 108 m/s

The range in kilometers to an object can be found by measuring the
elapsed time during a round trip of a radar pulse and dividing this quantity by 6.66.
The range in nautical miles to an object can be found by measuring
the elapsed time during a round trip of a radar pulse and dividing this quantity by 12.36.